What is glaucoma?

Glaucoma is an eye condition where your optic nerve is damaged by the pressure of the fluid inside your eye.This may be because your eye pressure is higher than normal, or because of a weakness to your optic nerve.

The anterior chamber of your eye (the inside of the front of your eye) is filled with a watery fluid called the aqueous humour. This fluid creates a pressure in your eye, which keeps it healthy and in the right shape. Your eye pressure is known as your intraocular pressure (IOP) and it isn’t connected to your blood pressure in any way. The aqueous fluid, which is inside your eye, is different from your tears. 

Aqueous fluid is produced in a ring of tissue, called the ciliary body, behind the coloured part of your eye, the iris. It flows through the pupil and drains away through a spongy network of holes called the trabecular meshwork. This sits in the angle where your iris and cornea, the clear front surface of your eye, meet. 

Usually, aqueous fluid drains away at the same rate as it’s produced to keep your eye at the correct pressure. The normal range of eye pressure is roughly around 10 to 21mmHg (mmHg stands for millimetres of mercury and is the measurement used for eye pressure).

If the fluid cannot leave your eye as quickly as it’s produced, your eye pressure will build up. This pressure can cause damage to your optic nerve at the point where it leaves the back of your eye. This damage is called glaucoma.

For more information on the different types of glaucoma see What are the different types of Glaucoma?

There is currently no treatment to restore sight loss caused by glaucoma but treatments, such as eye drops and laser surgery, can help prevent sight loss from happening.

You can get more information and advice on glaucoma by contacting the International Glaucoma Association (IGA):

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